Concentration of CO2 in the Atmosphere

Benefits to the Planet Heating with Forest Products

And how it is done sustainably

Jim Van Valkenburgh

You have probably talked to people with opposing views on using trees for energy. One says it is sustainable and another says it is not. (“It’s worse than coal!”) I propose that both can be right depending on where they are in the U.S. or the world. Sustainability largely depends on the availability and management practices of the forest resource in a given region.

A quick lesson on the natural carbon cycle: Trees grow and absorb CO2 (carbon dioxide) and then release it over time in different ways. If left undisturbed, limbs and trees fall and decay, releasing methane to the atmosphere as the remaining trees keep growing. A mature forest has a general stability of incoming and outgoing of carbon. Should a forest fire occur, a tremendous amount of carbon is released into the atmosphere, but after that, an increased rate of carbon absorption occurs due to new, rapidly growing trees taking root. Generally, carbon is fairly balanced, in and out.

People often think of unharvested forests as sequestering more carbon than harvested forests. Yes, when trees are removed there is an instant reduction in the sequestered carbon of that stand, but over time, the forests respond to a more open canopy, more sunlight and resources, to grow into a healthier, stronger and more vibrant and resilient forest. So, you can achieve more carbon storage in a managed regime. This is part of silviculture.

Most forest owners have the same goal: Keeping their forests as forests. In the Northeastern U.S., forest owners can be put into three groups:

  1. Small owners (1-50 acres) will cull out the dead and dying trees, using it for cord wood for themselves and others to heat their homes.
  2. Owners of larger stands (50-250 acres) will hire a professional forester and logging company to manage that. Their goal in doing this is to sell the cut trees so they can pay their forest management expenses and property taxes. Typically, 30% of the trees are valuable while 70% are useful only as fuel.
  3. The paper and lumber companies which own the huge stands (250+ acres) use foresters and best practices that will enable them to keep their forests productive and profitable for centuries.

The new steam boiler at Mill River Union High School in North Clarendon, VT uses dried wood chips. The silo holds over 40 tons of chips, with energy equal to that of 4000 gallons of heating oil. Photo credit: Froling Energy

A few million years ago fossil fuels were once trees and plants. When we burn them today, there is no natural cycle that returns them back to the ground. Some say, “Let our forests eat up all that carbon!” In recent decades, more wood has grown each year in New England than has been harvested, specifically in VT and NH, but consider how much oil, gas and coal is being burned each year. Forests can only make a small dent.

For 10,000 years, atmospheric CO2 levels were very stable at 270ppm. This chart shows the last 140 years of CO2 emissions by fuel source and land-use change (forest to farming). Around 1900, as we expanded our use of fossil fuels, levels began to rise. When oil and gas use skyrocketed in the 1940s and 50s, atmospheric CO2 has risen precipitously.

What should we surmise from all this?

Forests, if harvested and maintained sustainably, will account for a steady cycle of carbon out and back in again. It is our intensifying use of fossil fuels that is causing increasing CO2 in the atmosphere. Our rural forests have been sustainably managed during the past 40-plus years, which means we can use trees to offset the use of fossil fuels for heating–without regret. Our forests function within the natural carbon cycle. So, relax. If you heat your New England house with cordwood or your local school with wood chips or pellets, you are doing your part to cut back on fossil fuel use and reduce CO2 in the atmosphere.

Jim Van Valkenburgh is the Vice President of Marketing at Froling Energy.

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